The present invention relates to a solid-state imaging device having an organic photoelectric conversion layer that generates electric charge in response to received light. Particularly, the present invention relates to a solid-state imaging device having a high degree of heat resistance.
As image sensors used for digital still cameras, digital video cameras, cameras for cellular phones, cameras for endoscopes, and the like, solid-state imaging devices (so-called CCD sensors and CMOS sensors), in which pixels having photodiodes are arranged on a semiconductor substrate such as a silicon (Si) chip, and signal electric charge corresponding to photoelectrons generated by the photodiode of each pixel is obtained by a CCD-type or CMOS-type readout circuit, are widely known.
As solid-state imaging devices, planar photodetectors, in which photoelectric conversion portions two-dimensionally arranged in a semiconductor are used as pixels and signals generated by photoelectric conversion in the respective pixels are electric charge-transferred and read out by a CCD or CMOS mode, are widely used. Conventionally, the photoelectric conversion portion is generally formed by making a PN junction in a semiconductor such as Si.
In recent years, as the number of pixels has been increased, the pixel size has been further reduced. Accordingly, the area of a photodiode portion has been reduced, and this has led to problems such as decrease in aperture ratio and light-collecting efficiency. As a technique of improving the aperture ratio, and the like, solid-state imaging devices having an organic photoelectric conversion layer using an organic material are being examined.
The solid-state imaging device having an organic photoelectric conversion layer is configured with pixel electrodes formed on a semiconductor substrate in which signal readout circuits are formed, an organic photoelectric conversion layer formed on the pixel electrodes, a counter electrode formed on the organic photoelectric conversion layer, and a sealing layer formed on the counter electrode, color filters, and the like.
In the solid-state imaging device, when bias voltage is applied between the pixel electrodes and the counter electrode, an exciton generated inside the organic photoelectric conversion layer is dissociated into an electron and a hole, and a signal corresponding to the electric charge of the electron or hole that has moved to the pixel electrodes according to the bias voltage is obtained by a CCD-type or CMOS-type signal readout circuit.